The present disclosure relates to a method for calibrating transient behaviour of an electrostatic discharge (ESD) test system.
Several measurement methods are used to assess the robustness of devices under test (DUT) under Electrostatic Discharge (ESD). These methods apply predetermined, standardized pulses to the DUT in order to simulate an ESD event.
Human Body Model (HBM) and Machine Model (MM) testers make use of transient pulses having a fast rise time (e.g. 2-10 ns) and longer decaying times (e.g. about 150 ns). Recently, testers have been developed by which both the resulting voltage and current waveforms on the DUT can be captured. One such tester is the Hanwa HED-W5000M, described in Japanese Patent Application 2006-182908.
Transmission Line Pulse (TLP) testers use rectangular pulses of successively higher amplitudes, wherein the voltage (V) across and current (I) through the DUT are recorded at the top flat region of the applied pulses. Compiling these I-V point pairs, the TLP I-V curve is obtained. An exemplary TLP tester is disclosed in US 2004/0239346 A1.
Human body model (HBM) and transmission line pulse (TLP) testing are common measurement methods to assess the robustness of devices under electrostatic discharge (ESD) stress. While HBM is mainly used for product qualification, TLP is traditionally performed on stand-alone ESD protection structures as a tool for optimizing devices as well as assessing the intrinsic technology capabilities. One of the disadvantages of a conventional HBM tester is that, as a standardized ESD test method, it only yields ‘pass-fail’ data for product qualification. TLP has a major disadvantage because it is not a standard test to qualify a product. As a result, different testers are used for product development and qualification, which roughly doubles the time and effort spent to ensure ESD reliability.
In Gauthier, R. et al., “TLP Systems with Combined 50 and 500 Ohm Impedance Probes and Kelvin Probes,” IEEE Transactions on Electronics Packaging Manufacturing, IEEE, vol. 28, no. 3, July 2005, pages 213-223, a measurement system with two different loadlines (50 and 500 Ohm) is presented which allows the study of a device under test in two different operation regions. Also, the Kelvin probe principle is applied to TLP testing in order to minimize the influence of contact resistance variations on the measurement data. A TLP system is discussed of which only a quasi-static (non-transient) calibration routine (resistance removal) is demonstrated.
Barth, J. et al., “TLP Calibration, Correlation, Standards and New Techniques”, IEEE Transactions on Electronics Packaging Manufacturing, IEEE, vol. 24, no. 2, April 2001, pages 99-108, focuses on TLP measurement systems. Several topics are covered: quasi-static TLP measurement data and its calibration, study of correlation of TLP failure level to HBM failure level and dV/dt effects in TLP waveform data. The presented waveform studies look at the TLP waveform without providing a general calibration methodology for this type of measurement data. The demonstrated calibration methodology relates only to the quasi-static part of the waveform.